CHROMIUM. 45 



J. Lefort : 52.97 (O = 16). 



Determined by fourteen experiments on the precipitation 

 of barium with sulphuric acid from a nitric acid solution of 

 barium chromate. The barium chromate was prepared by 

 precipitating potassium chromate with barium nitrate and 

 drying the precipitate at 250°. [If these analyses are cal- 

 culated for barium = 137 and S = 32, they give 100 barium 

 chromate = 60.244 barium oxide, extreme difference, 0.26, 

 and the atomic weight as above. Lefort seems to have 

 taken Ba = 136.72. Berlin points out the correction which 

 I have verified.] {Erdmami's Joarii. filr Prak. Ohem., 51, 

 1850, 261 ;" Journ. de Pharm. et de C/wn., 18, 27.) 



R. WiLDENSTEIN : 5S485 (O = 16). 



Determined by thirty-two experiments on the precipitation 

 of barium chloride, desiccated at a red heat, by pure, neutral 

 potassic chromate. The mean of these analyses gave 100 

 barium chromate = 81.70 barium chloride ; extreme differ- 

 ence 0.35. Wildenstein calculates 334.48 without giving 

 the assumption for chlorine. [If CI = 35.457 ; Ba = 137, 

 the value follows.] {Erdmann's Journ. fw' Prak. Ghem., 59, 

 1853, 28.) 



F. Kessler : 52.3 (0 = 16). 



Kessler reached this value by comparing the oxidizitig 

 action of potassic chromate with that of potassic chlorate on 

 arsenious acid. Six experiments were made on the oxidiz- 

 ing power of the chromate and twelve on that of the chlorate 

 by a method of titration. By combining the maximum of 

 one with the minimum of the other series, Kessler finds the 

 atomic weight of chromium between 25.93 and 26.40 ; in 

 mean 26.15, K being = 39.12 and CI = 35.45. Confirma- 

 tory experiments were made on the oxidation of ferrous 

 chloride in the same way. These gave a mean of 26.1. 

 {Poggend. Annul, 113, 1861, 137; 95, 1855, 208.) 



M. SiEWART : 52.094 (0 = 16). 



Determined from the amount of chlorine in sublimed 

 violet chromium chloride. Siewart criticises Kessler's de- 

 termination and deduces from the latter's data a value 25.02. 

 {Kopjy's Jahresbericht, 14-, 1861, 240; Halle, Zeitschr. fiir die 

 Gesammt. Naturwis., 17, 530.) 



Kessler points out that the number 25.02 is a misprint in 

 the Jahresbericht, and that Siewart's paper ascribes to him 

 the value 26.02. {Poggend. Ann., 117, 1862, 352.) 



